Duchenne muscular dystrophy (DMD) results from a lack of which protein, which normally helps thin filaments of myofibrils bind to the sarcolemma?

1. DMD is a progressive, inherited weakening of skeletal muscle caused by an abnormal X chromosome. 2. The missing protein in DMD is dystrophin, which normally helps thin filaments of myofibrils bind to the sarcolemma. 3. Without enough dystrophin, contractions tear the sarcolemma, causing calcium influx, cellular damage, and progressive fiber degradation. 4. Tropomyosin, calmodulin, and myoglobin all have separate roles in muscle physiology and are not the protein missing in DMD. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 10 "Muscle Tissue", section 10.3, p. 421_